Field of Technology
The present disclosure relates to a flexible display device.
Discussion of the Related Art
Recently, with the advancement of the information age, display devices for processing and displaying a large amount of information have been rapidly developed. In response to this trend, various display devices have been introduced and spotlighted. Detailed examples of the display devices include liquid crystal display (LCD) devices, plasma display panel (PDP) devices, field emission display (FED) devices, electroluminescence display (ELD) devices, and organic light emitting display (OLED) devices.
Among the display devices, the organic light emitting display device based on an organic light emitting diode has advantages in that the organic light emitting diode provided in a display panel has high luminance and low operation voltage property. Also, since the organic light emitting display device is a self-light emitting device that has a good contrast ratio, it is advantageous in that the organic light emitting display device realizes an ultra-thin display. Also, the organic light emitting display device has a response time of several microseconds to easily display moving images, has no limitation in a viewing angle, and is stable even at a low temperature.
Recently, efforts for realizing a flat panel display device as a flexible display device to realize various objects such as easy portability, various types and damage avoidance have been made. For example, a liquid crystal display device and an organic light emitting display device are arranged on a flexible substrate such as plastic, whereby a flexible liquid crystal display device and a flexible organic light emitting display device can be manufactured.
However, to have a bending property of the flexible display device, development of a bending property of inner elements of the display device in addition to the flexible substrate has been required.
Also, in accordance with the application of a flexible property to the display device, a bezel bending technique has been introduced, which minimizes a bezel width by bending an area corresponding to a bezel portion where image is not displayed.
FIG. 1 is a plane view illustrating a conventional flexible display device based on bezel bending, FIG. 2 is an enlarged view illustrating an area A of FIG. 1, FIG. 3 is a cross-sectional view taken along line I-I′ shown in FIG. 1, and FIG. 4 is a cross-sectional view illustrating that a bending area of FIG. 3 is bent.
Referring to FIGS. 1 to 4, the conventional flexible display device based on bezel bending includes a display area 1, a non-display area 2, a bending area 3, a gate-in-panel (GIP) area 4, and a driving portion 5.
The display area 1 is an area where an image is displayed, and the non-display area 2 is an area where an image is not displayed. A part of the non-display area 2 includes the bending area 3 of a bent type. The GIP area 4 is an area where a gate driving circuit is arranged inside a display panel where a thin-film transistor (TFT) substrate is formed.
The display area 1 and the non-display area 2 include a substrate 25, a polyimide layer 24, a multi-barrier layer 23, an inorganic layer 22, a gate insulating layer 12, a dielectric inter-layer 21, and a passivation layer 20.
In this case, a thin film transistor layer T, a planarization layer 30, an anode electrode 40 and an auxiliary electrode 50 are formed on the display area 1. The thin film transistor layer T includes an active layer 11, a gate insulating film 12, a gate electrode 13, a dielectric inter-layer 14, a source electrode 15, and a drain electrode 16.
A bank 60 is formed on the anode electrode 40 and the auxiliary electrode 50 to define a pixel area, an organic light emitting layer 70 is formed in the pixel area defined by the bank 60, and a cathode electrode 80 is formed on the organic light emitting layer 70.
In the aforementioned conventional flexible display device, as shown in FIG. 4, the bending area 4 is bent to minimize a bezel corresponding to a part of the non-display area 2. At this time, a crack may occur in a source electrode 15 connected from the thin film transistor layer T. Therefore, the conventional flexible display device uses a line having the same shape as a pattern of FIG. 2 to reduce such a crack.
However, in this case, the source electrode 15 is not disposed on a neutral plane, whereby the crack occurring in the source electrode 15 is not avoided fully.
Also, in this case, a problem occurs in that it is impossible to apply the line of FIG. 2 to a high resolution display device due to a distance P between lines and a width L of the lines as shown in FIG. 2. This is because there is restriction in design of the line due to an area reserved by the distance P and width L of the lines relatively increased in the high resolution display device.